The present invention relates generally to the preparation of concentrated fibrinogen from blood for making fibrin glue and, more particularly, to the autologous preparation of relatively small quantities of concentrated fibrinogen for making fibrin glue.
Fibrin glue has been found to have widespread applications in various medical and surgical procedures. For example, fibrin glue is used as an adhesive for sealing various internal wounds or incisions in body organs. The glue also serves as a good tissue adhesive. Concentrated fibrinogen, which is used in making the fibrin glue, is initially prepared from human blood and stored for use at a later time during surgery.
A description of a technique for preparing fibrin glue from blood may be found, e.g., in Vascular Surgery, Volume 17, No. 5, September/October 1983, pp. 294-304. Generally, the amount of blood is collected and, after addition of sodium citrate as an anti-coagulant, centrifuged to form supernatant plasma. The plasma is collected and then frozen, e.g., at -80.degree. C. for at least 6 hours. The frozen plasma can be stored for periods of over one year. Just prior to surgery, the frozen plasma is thawed at 4.degree. C. for six hours. The thawed plasma is cold centrifuged to obtain a sediment of concentrated fibrinogen. Thrombin is added to the fibrinogen during the surgical procedure to produce fibrin glue for administration to the patient.
While this technique for preparing concentrated fibrinogen from the blood of one individual and administering fibrin glue produced from the fibrinogen to another individual has been widely adopted in Europe, its use is not presently permitted in the United States due to the possibility of transmission of infectious diseases, such as hepatitis or AIDS, from one individual to another. Accordingly, in the United States, only autologous synthesis and use of fibrin glue, i.e., preparation of the fibrin glue from the patient's own blood for use during his own imminent surgery is permitted. However, such autologous synthesis of fibrin glue has suffered from several drawbacks.
For example, it has not been possible to prepare relatively small quantities of concentrated fibrinogen for immediate use in a practical manner. The equipment and instruments for extracting the fibrinogen are generally large and located at places remote from the operating room. Such equipment is not suited for extraction and production of small quantities of fibrinogen.
Furthermore, since the preparation of larger quantities of concentrated fibrinogen requires longer times, the patient may be required to be admitted to the hospital earlier than otherwise indicated in order to provide sufficient time for the preparation of fibrinogen.
For these reasons, autologous preparation and use of fibrin glue has not been actively pursued in medical and surgical treatment in the United States.